tachysterol

[tə-kĭstə-rôl′, -rōl′]

n.

An isomer of ergosterol that forms vitamin D2 when irradiated with ultraviolet light.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.